Metatag Annotation for new submodule

It sounds like uou'll need to extend MetaNameBase::form(), MetaNameBase::value() and MetaNameBase::setValue(), possibly some others too. If you want to have test coverage you'll also need to extend MetaNameBase::getTestFormXpath(), MetaNameBase::getTestFormData(), MetaNameBase::getTestOutputExistsXpath() and MetaNameBase::getTestOutputValuesXpath().

#2 after digging a bit into other implementations I see a light at the end of the tunnel.

My class looks like this

<?php

namespace Drupal\metatag_csp\Plugin\metatag\Tag;

use Drupal\Core\Form\FormStateInterface;
use Drupal\metatag\Plugin\metatag\Tag\MetaNameBase;
use Drupal\Core\StringTranslation\StringTranslationTrait;


/**
 * Provides the Content Security Policy (CSP) meta tag.
 *
 * @MetatagTag(
 *   id = "csp",
 *   label = @Translation("Content Security Policy"),
 *   description = @Translation("Specifies the Content Security Policy directives for this page."),
 *   name = "csp",
 *   group = "advanced",
 *   weight = 10,
 *   type = "http-equiv",
 *   secure = TRUE,
 *   multiple = FALSE
 * )
 */
class ContentSecurityPolicy extends MetaNameBase {

  use StringTranslationTrait;

  /**
   * {@inheritdoc}
   */
  public function form(array $element = []): array {
    $form = [];
    $form['csp_default_src'] = [
      '#type' => 'details',
      '#title' => $this->t('default-src Directive'),
      '#open' => TRUE,
    ];

    $form['csp_default_src']['default-src'] = [
      '#type' => 'radios',
      '#default_value' => "",
      '#options' => [
        'self' => $this->t('Self'),
        'none' => $this->t('None'),
        'any' => $this->t('Any'),
        'n/a' => $this->t('n/a')
      ],
    ];

    $form['csp_default_src']['additional_resources'] = [
      '#type' => 'textarea',
      '#title' => $this->t('Additional Resources'),
      '#default_value' => "",
      '#description' => $this->t('Specify additional resources for default-src.'),
    ];

    return $form;
  }
}

When I go to a page and save my changes, I notice that the values are not saving and I am struggling to understand how this config can be saved and retrieved if exists.